Air-Secure-Module-Loading is a project mainly written in ..., it's free.
Secure (signed) module loading for Adobe Air apps
A framework for securely loading 'modules' (swfs) into Air apps.
Interested? Read more here.
What's in the tools folder?
A benefit of modular development is that you can do frequent releases - but packaging up swfs to signed zips, and uploading them to your server, can be a bit time consuming, so there's a script in there that automates those steps, and an example -app descriptor file that is set up for the version numbering to change.
I still like to update the required version number manually - it allows me to push up a new set of modules and release them together, or to a group of 'beta' users ahead of releasing to everybody.